Electromagnetic circuit controller



Aug. 29, 1950 1.. BEEMAN ELECTROMAGNETIC CIRCUIT CONTROLLER 6Sheets-Sheet 1 Filed Feb. 22, 1943 IN VEN TOR.

ATTORNEY.

A 2 1950 L. BEEMAN 2,520,708

ELECTROMAGNETIC CIRCUIT CONTROLLER Filed Feb. 22, 1945 s Sheets-Sheet 2IN VENTOR.

BY 99/6 0%eeman W ATTORNEY.

\ Aug. 29, 1950 BEEMAN,

ELECTROMAGNETIC CIRCUIT CONTROLLER s Sheets-Sh ei: s

Filed Feb. 22, 1943 INVENTOR. 0 9/2 (7566712012 ATTORNEY.

g- 29, 1950/ L. BEEMAN 2,520,708

ELECTROMAGNETIC CIRCUIT CONTROLLER Filed Feb. 22, 1943 s Sheets-Sheet 51N VENTOR.

BY (fieeman ATTORNEY Aug. 29, 1950 L. BEEMAN ELECTROMAGNETIC cmcuxwCONTROLLER 6 Sheets-Sheet 6 Filed Feb. 22, 1943 v i I INVENTOR.'c'fieemqm ATTORNEY.

Patented Aug. 29, 1950 ELECTROMAGNETIC CIRCUIT CONTROLLER Lyle Beeman,Ann Arbor, Mich., assignor'to The Master Electric Company, Dayton, Ohio,a cor-' poration of Ohio Application February'22, 1943. Serial No.476,667

This invention relates to electromagnetic controllers for electricmotors and the like.

This application is a continuation in part of my copending applicationSerial No. 282,857, filed July 5, 1939, and which has matured intoPatent No. 2,371,601.

l/fysaid copending application discloses an improved electromagneticcontroller in which a single pilot switch performs the dual function ofa start and stop switch.

One object of the present invention is to further improve theconstruction and operation of controllers of the type shown in saidapplication.

A more specific object is to provide an electromagnetic controller inwhich the main switch mechanism is rendered responsive to the electromagnetic actuator by a direct action so trans: mitted as to permit afree self-centeringadjustment between the actuator parts.

Another object is to provide an electromagnetic controller in whichalignment between the main switch parts is accurately maintained withoutinterfering with a free self-aligning action between the parts of theelectromagnetic actuator.

Another object is to provide an electromagnetic controller of simplecompact design in which all the essential parts are readily accessiblefor inspection and readily removable for replacement or repair.

Another object is to provide an electromagnetic controller having asingle button control switch an automatic indicator for showing whetherthe switch is open or closed.

Another object is to providea simplified and improved single-buttoncontrol switch for electromagnetic controllers.

Another object is to provide a single-button control switch forelectromagnetic controllers in which the start stroke of the controlbutton is greater than the stop stroke thereof.

Another object is to provide an improved unitary control switch forelectromagnetic controllers capable of functioning as a start switch astop switch and a holding switch whether applied directly to theelectromagnetic controller or at a remote control station.

Another object is to provide a unitary control switch having electricalmeans for holding the same closed automatically so long as theelectromagnetic actuator of the main switch is energized.

Another object is to provide remote control switch mechanism of compact,simplified and improved construction.

Another object is to provide in an electromag- 3 Claims. (Cl. -294)netic controller an improved holding switch therefor for use with remotecontrol switches.

Other more specific objects and advantages will appear, expressed orimplied, from the following description of an electromagnetic controllerembodying the present invention.

In the accompanying drawings:

Figure 1 is a front elevation of an electromagnetic circuit controllerconstructed in accordance with the present invention.

Fig. 2' is a vertical section taken substantially along the line 2-2 ofFig. 1.

Fig. 3 is a side elevation.

Fig. 4 is a fragmentary transverse section taken substantially along theline 4-4 of Fig. 3.

Fig. 5 is a detail view in perspective of the energizing coil shown inFig. 1.

Fig. 6 is a detail view in perspective of the ooacting sections of theelectromagnet.

Fig. 7 is a front elevation of the control switch shown in Fig. 2. g

Fig. 8 is a rear view of the control switch of Fig. '7.

Fig. 9 is a vertical sectional view of the same control switch.

Fig.10 is a circuit diagram including the control switch of Figs. 7, 8and 9.

Fig. 11 is a front elevation of a remote control switch for one remotestation.

Figs. 12 and 13 are rear elevations of the control switch shown in Fig.11 illustrating the same in open and closed condition, respectively.

Fig. 14 is a vertical sectional view of the control switch shown in Fig.11.

Fig. 15 is a face view of a terminal panel for use with the controlswitch of Fig. 11.

Fig. 23 is a circuit diagram including the com trol switch and holdingswitch. shown in Figs; 18 and 21 respectively.

'Fig'. 24 is a plan View of the overload snap switch shown in Fig. 3. I

The electromagnetic controller selected for illustration is showncarried by a mounting plate seated on a base plate of like material. The

separator plates I4 cooperatewith'th'ban flia'r'id bar plate l5 to formseparated ,cells each containing a pair of stationafy'switch contacts T6and H.

The forward switch contact l 6 of each pair is carried by one leg of aU-shaped conductor strip [8 embracing the forward edge of the bar lg andfixed in place by a screw 19 which also'sives'as tin n 99 t. qrleem gn ihngnel m r z i i' p cpit The oth' W th? j 1f i t .5 m l l a e lu iewleaq n a mdwt fir fi mbm the r ar ed e or the bar ,[sf and confinedtbythev pla'tej] 5, the rrll 2 t sim 2 11 7 a u ardl bent portionfliadapted toreceive nd' support a esecond bindingfpostjl for connectionwith o'ige ea r mor or 'other work circuit m u tin P 1 lit APP 1 in atem i ifw as 'a'pair of bra'cket 'p ates '23, elach fi ed to 'an end plateIt thereof a'clr bent to "provide a m et rfla ee 145d? Q'ab fi e to themounting plate lillby s'c're s rtne like.

I e ermi i ibldikt 2: 3 .9 ir i J- l ii ti ye-z this. ns-tame. aq o sz eluld by two vertical slide pins 29; each projecting dow war ly intq me dthecrQss-he iland releasably s'ecured therein by appropriate nifeans IVe 3l in such as a screw. 36, fin aged in ag the'p'in. 'Ea'c h'pin 2a isfitted r0;- fr efleiigtnmo me t W hi -awai 9L eamm "guides 32 which in,.thisin'stance are termed by striking; up and suitablybendingport 'risoifeach bracket 9 5E2 1 he s' eadzfi'a so n r all rests, L iie t ib w hlip .nd 3 'Qtf 11 I o ve mentioned pairs of "'tatio a'ry contacts "Landl'l're e cpe actuator nam p ate be 'herinarte described, and it isre'cesised as at 35,10 accommodate the separatorplates 'l carried by theopposite ends of a bridge member 36 of copper or other rgood conductingmaterial. lilach b'ridgie member, is/ supported intermediate its endsupon a coiled spring}! seated infand projecting from a socket ,38 formed'ijn'the cross- ,h 'adz aridyr t i dg n ma e by nfan ror i t 'tie'inemberin the formjofj a Uf'shaped spring Iclip 39. The lower endofeach. tie' member iifl is seated in a square socket 4ll'lorrheddnfthecrossrhead 2 6 ,and is releasablyv retained; place .by asciew M or thepretext nfding thereth'roiigh. Eachtie 'm'e H be'r, tipardi h h jS- re ben e f h bent outwardly in opposite .lfi g laslw c coact t the-1 3351bridge member to limit "the iupward n1fov q i .thereof. r.elative ,to,.the "pros he" d 126 lr depie fi ma ree' y vem V ing together the legs'ofthe 'tie iielnbe'i" 39 seas Each pa r 0% ovab nta ts 21 and Bet ie, ve.4 are preferably magnetically 'se rated from the "es and the"Mghwrdframe v metal having a central stnrenmg rib "so "which 4 to permitthe fingers 43 thereof to pass through the opening 42. In that Way anybridge piece 36 with its switch contacts 21 and 28 may be readilyremoved for replacement, cleaning or repair.

The mounting plate 10 also provides support foran electromagnet by,which the crosshead 26 actuated The' electronijag net show'n comprisesan E-shaped stationary field section 44 coacting with a similarly shapedmovable arma- 't'iire section 45, both being composed of laminations ormagnetic material riveted together between upper and lower frame plates46 and 41, res ectely V section 44 is carried by an appropr ate: m ntrig bracket 48, attached to the plate 10', and its center leg 49provides support for an energizing coil 50 surrounding the same.In'tliisins tance the coiljil is positioned by a pair i RQVWWIQY ifl fidm P t ex din the'rethrough The 'clips '51 are bolted or otherwiserixedfat efend tothe fieldsctionllexte d lengthwise ofjandbfey ond thecenter lgas th qg gafid ar :b e .a g ri r ot r'i wriivideoutwardprotuberanc'es 52 by which the 6011 50 1s releasablyretained, as indicated particularly'," Figs. 2 "an '5, rt iwi 'ib'eno't'ed that the @0 1 *5! ma arem i me lf placemen or repair byforcing the same axially over the protuberances Slfl he ioifable "amature sec- ,tion '45 has as cefr'itralleg 53 projecting into the coila" d fg'uidedby andbetwnfthe clips! I A (limited-particularly in Figffi,one or both i A w ia ea u fe fd bf jacent' laminations, thereby"''roviding two te hirlgapsjfi Jane 5 1 'within; the mag ea 'Thelaminations "the earli r *l'g outeijjran e plates Miand ll'lbysheets-'of copper br'other lrionf-rmag the materiafiiiteipfied "belidtherivets"'by H r s"are;'bou'iid'together are' preferably "of" n'on'magnetic material qrfi ilsa elev sl Motion is imparted to 'ftiiestitch-"carrying cross-head 26 from the "aerate armature's'ecfergbwjmsuch marinate retr eve the center self titties-peat 'to te-ecu stationary section 44. In this "instance this is accomplished bythe use of a eta anew.wi ms e e am "sid emanates; 46 and' l'l The rentedit: a stri or tends gac'ross the base of. the 'irame'as tv ell'as alongboth legs thereof :At ajiiiid 'p'oifit along "thebase of the frame,therib 6llb'earsagainst a bolt 6| fixedinsupporting ears tigonthearmalture section tqprovidea freely flexi fl iin la point drivingengagement between the section 5aedgfreme-H,

"Ashereinabove noted; the il'ppel ends "33 Of the frame 34 are in thrustengagement with the switch-carrying cross-head '28. It will of course beunderstood that when the armature section 45 is forced upwardly byenergizing the coil 50, this motion is transmitted through the bolt SIand frame 33 to the cross-head 26 to advance the switch contacts 21 and28 into contact with the stationary contacts I6 and I1, respectively, toclose the switch, and when the coil 5|] is de-energized, the cross-head26, frame 33 and armature section 45 fall by gravity to separate theswitch contacts and open the switch. It will also be understood thatwhen the contacts 21 and 28 are thus pressed against the contacts I6 andI7, the springs 37 are compressed so as to insure adequate pressurebetween the contacts, the springs 31 also serving to impart an initialdownward impulse to the cross-head 26 during each downwardswitch-opening movement of the latter.

An appropriate stop 63 mounted on the plate IO N coacts with the bolt 6|to limit the downward movement of the armature section 45 of theelectromagnet.

The'coil 58 of the electromagnet is energized from the main powercircuit by including the same in a control circuit shunted across two ofthe binding posts I9. The coil 58 is controlled by appropriate switchmechanism disposed either within the housing II or outside of thehousing at one or more remote stations, or by both. A pilot switch,particularly adapted for use within the housing, is shown in Figs. 7, 8and 9. The switch therein shown is contained in a molded plastic housing64 having integral mounting ears 85 projecting from the sides theerof,adapted to seat upon the inturned flanges 61 of a pair of appropriatebracket plates 68 fixed to and projecting from the mounting plate II! atopposite sides of the electromagnet. The mounting ears 65 may be fixedto the flanges 61 by screws 68 or the like. A pair of stationary switchcontacts 69 are carried by suitable mounting plates I8 within oppositelower corners of the housing 64, each being electrically connectedthrough separate leads II to suitable binding posts 12 atattachedintermediate its ends to the outer end of a plate-like lever structureI5. The lever is rockably supported intermediate its ends upon a shaftI6, fixed at its ends in the opposite side walls of the housing 64. Anappropriate spring 11, acting on the inner end I8 of the lever 15 urgesthe same in such direction as to separate the movable contacts I3 fromthe fixed contacts 69. An actuating arm I9, projecting from a midpointof the lever I5, has a bifurcated end carrying a pin 88 engaged in aslot 8! in one end of a rocket element 82 mounted upon a fixed pivot pin83. The pin 83 spans a rectangular recess 84 formed in the base of acylindrical socket member 85 which projects beyond the face of thehousing 64.

The rocket element 82 and switch lever I5 are, in this instance,actuated by a single push button 86 axially movable within the socketmember 85 and having a bifurcated shank 81 which straddles the rockerelement 82 and having guide slots 88 in which the pin 83 is engaged. Thepush button 86 is urged outwardly by appropriate means, such as a spring89. A dog 90 is rockably supported on a pin 9| between thelegs oftheshank 81, and a leaf spring 92- coacts with the push button 85, thepointed end 94 of thedog will enter one or the other of the recesses 96or 9! and force the rocker element 82 to rock in one direction or theother, to thereby actuate the lever and open or close the pilot switch.If the switch is open at the time that the push button is depressed, theprojection will direct the pointed end 95 of the dog into the recess 86,causing the switch to close; and if the switch is closed, the projection95- will direct the pointed end into the other recess 51, causing theswitch to open.

The parts are preferably so proportioned and arranged that the pilotswitch will not close except by depressing the button 86 downwardly intothe socketed member below the projecting rim so thereof, so that theswitch cannot be- 'closed except by a deliberate act on the part of theoperative, thereby avoiding accidental closing thereof. particularly incases of emergency, that the: switch be readily openable by pressure onthe button 86, however applied, and for this reason the operating strokeof the button 88 for the switch opening operation is less than for theswitch closing operation, the switch opening operation being completedbefore the button 86 has been depressed below the rim 98. Although thisvariation in operating stroke of the button 85 may be accomplished invarious ways, in the device shown, the recess 95 is formed somewhatdeeper than the recess 9! for that purpose.

Provision is also preferably made for indicating the open and closedcondition of the pilot switch. In this instance a shallow rectangulardepression as is provided in the face of the switch housing 64 with thewords Off and On lettered on the base of the recess in vertically spacedrelation. These words are alternatively exposed by a shutter plate IE8reciprocable over the base of the recess, This plate its is operativelyconnected to the switch lever l5 through appropriate means, such as apair of fingers IfiI carried by the inner end I8 of the switch lever andprojecting through slots I52 into apertures I53 in the shutter plate.The arrangement is such that when the switch is open the shutter plateIDS is in such position as to expose to view the word Off, as indicatedin Figs. '7 and 8, and when the lever I5 is actuated to close theswitch, the plate I88 is thereby shifted into position to expose theword On.

Provision is also preferably made for automatically holding the pilotswitch closed when the main switch is closed, and for this purpose aplunger lot is provided reciprocably mounted in andprojecting from thelower end of the housing 64. The outer end I85 of the plunger I84projects into the path of travel of a resilient finger I85 carried byand projecting from the movable armature c5 of the electromagnet, asindicated particularly in Figs. 2 and 6. A coil spring I8: yieldablyretains the plunger M4 in the projected position shown, but whenever thearmature 45 moves upwardly to close the main switch, the spring fingerI85 carried thereby engages and forces the plunger I84 upwardly againstthe end '58 of the switch lever I5 to yieldably hold the pilot switchclosed. r

However, it is highly desirable.)

t will o rse be understood th twheeever the armature 45 lowerstaopen.the. .ma 1n eti e ly. wi k.

switch, the plunger til is aut drawn from the switch lever by the-actionof the spring I61 to permit thepilotswitchto.{m n

under the action of the spring l'l; andjiii-will be understood that thepilot switch may be manually opened, to de-energize the coil 59,,whilethe armature 45 is in its upper'switch closing nections with thestationary switch contacts .55

thereof. The control circuit I03 also includes two normally closedoverload switches 1-69, to behere: inafter described, either ofwhich'may open under certain predetermined conditions to thereby.automatically de-energize the coil 50 and efiect. Opening of the mainswitch.

The pilot switch shown in Figs. 11 tom is similar in many respects tothat shown in Figs. 7, 8 and 9. It is contained within-a molded b.0113:ing 6 adapted to be arranged at any. convenient control station remotefrom. the housing l'l. Two stationary switch contacts 89, separatelycon. nected to binding posts 72', ,coact. with movable. switch contacts1.3 carried by the .oppositeends, of a resilient metallic bridge piece.'14.

In this instance. the bridge piece i4 is carried by a plate-lilielever55' which is actuated and controlled by a single push button 85 throughmechanism substantially the. same asfthat. employed in the. pilot switchfirst above. desgribed. including the shank 8'! of the push-buttonlfif.the .dog; ,Qfi'carried thereby. the notched rocker element 8 2, and thearm '19. projecting laterally from-amid point. of. lever 75.. The lever.15, is. biased toward switch opening position by aspiring. ll. Anindicator, including. a reciprocable. shut.-- ter. plate; i953,constructed and operated in the. manner above described is alsopreferably provided in order that the operative may know.

at a glance whether the switch is in open or;-

closed condition.

The pilot switch shown in Figs. 11 lac-1.41s also. equipped with meansfor yieldably retaining. the. same in closed .condition so long as the.coilS'Q is energized, but in this instance this. is. ac.com-- plishedelectrically preferably in a manner such as will now bedescribed. Inthis instance the. housing 64 is. extended toreceiv andhouse a suitableelectromagnethaving an energizing. coil H9; connectedin series with the:energizing. coil 58 of the electromagnetic actuator of the main switch.The coil H0. is. shown surrounding and supported by one leg I H of anL-shaped station arymagnet section H 2, An L-shaped movable armaturesection H 3 hingedly engaged. with the section H2, has a leg H4 which ismovable into contact with the: leg H-l whenever the coil Hit isenergized; and a suitable resilient. connection is provided between thearmature H3 andthe switchactuating. lever 15- through which the latteris; urged toward switch-closing position whenever the coil H0 is.energized; resilient connection shown for thisrpurposel in cludes a leafspring- 15 carried by the amazes;

section l lrs having abi furcated end Hiop'.

e ivc rg esae i h a mens s .1 moles? s item e ev r. 15-

The a angem nt such t a so l as th .0 i e ers zed 't old the ma n witcles ii the @011. I9 s l eene s z d an t e le 4 f e armatur is h e held.iewm

e i the-l e l H th ionary ction l 3. nd t e pr F5 is so. tens oned methe.

ever 5 m erd l eh o n p si io How.-

re b d e s ng the us b o 5.6 the is??? may be ct ated a n esis ance a ohe: p in '5 o thereb pe th swi chenq depc e z hoih i-l ill a W se est-efiect enin o the ma n witch.

.S.. ce the cont ol o the pil t switch Show 1. o; is s i an w r eP-e dcmme ha ic l nnect n b ween i sh ubs or: etine me h n sm o th main i ch.bi well ptedq r at a n un e. ion 19 i. ide of the ma n wi ch h sin H hee 9 mp oy d. nd for onv nien ei m kin c n: nections, a terminal panel II8 is preierably' used, lat e e m unted onhe bx slse nle lan es '5 witin hevme n hihousine- As n cated.- par i ar n His- 1 1. th 5- quopedwith wo b d n po s 1 1 .9. electric l connected through separate.conductors. l-,2-. l i with. two bindin post l2 r p tivel Th pane U8provides a convenient mean ior connecte; ing the pi-lotsw-i-tchintothecpntrolcircuit i 98. the bindin po s H5 i c nnect d to th ppositsides. respec iv ly, of hetc reu t. and. he b n post zibe e nnected to hwposite sides leaf. respectiv y. or thcpi-lct-swi h. al as i ted parcula y in- ;Fis- 1 16:

From inspection of Fig; 16:, itwill-be-notedthat whenever the pilotswitch 59' closed,.b9th H9. and iflare energized, the. latter h ou h t am t re wand-f ame .4- e-Fl ss the; m in wit h. ani n orm r. umt lsi -lst ou h e m-nature I: l3 o'l ld ho-r119; when cl edts-above te b w rn:the the pi ot w tch 1. will open au ca titellrr wh n the we: trolcircuit. l-fl8 is tie-energi ed, and also thatthe pilot w h .9 a bmanuall opened-wh le the. coil- H0; is energized and, whep. opened, bothcoils 5D. and l lflyare de -energized and main. switch opensautomatically.

Since the pilot switch shown in Figs. 11. 159 14 m y e. emp ou de-. :x fi .m i;n s itch housing. I I, and since it may. be opened or closedby prs r pp d toe single cont o lement as. i y li -re d ly o e ted-i to ammo?co trol swit h onsi e to re ure howev r applied. In Fig. H, for instanceit has lmw n ert i a p dant sw tm'ccnah e of being eitherclosed oropenertbya gripping p ess eol e y he and. en mels??- As e in sho n. h-eilotswi c r it i ts housiz e-lif ha b e mo e -with n .coll siblecontainer in the formv of anapxiliary' housing 122* having a cover H34hingedat igd thereon. The e y ri p o id d ith ae r s i 3.519 otherwisefashioned to bear against the. control but n Q-the :wh e r the cove L24s me s h u to 8 a tua ed t c os o to Or n h wi ch:- Th im h u i eii sepcrted bye l -22 contai in h wo' wi leadsl-.8 8{ and is of a size tobereceived within em pa edy eh n i a ope ative. h a n e en einsfiu hthat the wi ch may e o r o e me e rbr s nsend i p e hou i g a ts o erith n hc nret vcs hand. w tch may sheets-ones.

ated to close or open the same by pressure applied to the cover invarious other ways convenient to the operative. Such an arrangement ishighly desirable, particularly in cases of emergency.

The pilot switch shown in Figs. 11 to 14 is well adapted for use insystems employing only one remote control station. For systems involvingmore than one control station, a controlswitch of the two-button type,such as shown in Figs. 18, 19 and 20 is preferred. The control switchtherein shown is enclosed within an appropriate housing I28 having asuitable removable cover I29 perforated to accommodate two switchactuating push buttons I51 and I3I. One of the push-buttons I30 is astart button operable to momentarily close a normally open switch andthe other button I3I is a stop buttonoperable to momentarily open anormally closed switch. Both switches and their actuating buttons aresupported by a frame of novel construction, preferably such as will nowbe described.

The switch supporting frame shown comprises a base plate I32 ofinsulating material fixed to the bottom of the housin I28 by bolts I33or the like. The opposite ends of the base plate are reduced to formtongues I34 which are closely fitted in and extend through appropriateslots formed in end plates I35 of like material disposed at right anglesthereto. The end plates are fixed and braced by appropriate anglebrackets I 36 fixed thereto and anchored to the base plate by the boltsI33. A top plate I31 is supported by the end'plates I35 parallel to andspaced from the base plate I32. The opposite ends of the top plate arereduced to form tongues I38 fitted in and extending through appropriateslots in the end plates I35.

The base plate I32 of the frame provides support for a pair oflater-ally spaced stationary contacts I35, each being fixed to anL-shaped conductor plate I46 having one leg riveted or otherwiseattached, as at I4I, to thetop face of the base plate. The other leg ofeach conductor plate is laterally extended and carries a suitablebinding post I552. The stationary contacts I39 cooperate with a pair ofmovable contacts I43 to form a normally open start switch, the contactsE43 being carried by the endsof a metallic bridge piece I44 suitablyfixed to the shank I45 of a push button I35. The shank I45 extendsthrough and is guided by the top and base plates I31 and M2, the end I46of the shank being square and fitted in a square opening in the baseplate I32 to prevent it from turnin and to thereby hold the contacts I43aligned with the contacts I39. A spring I41 urges the button I36 andshank I45 outwardly so that the contacts I39 and I45 are normallyseparated and the switch normally open.

The top plate I31 of the frame provides support for a pair of stationarycontacts I48 carried by L-shaped conductor plates I49 similar toconductor plates I45, similarly attached to the under face of top plateI31, and similarly equipped by binding posts I56. And a metallic bridgepiece II carried by the shank I52 of the push button I3I is providedwith contacts I53 respectively aligned with contacts I48 and cooperatingtherewith to form a stop switch. The shank I52 is similarly guided bythe plates I31 and I32, and a spring I54 urges the shank I52 outwardlyso as to normally retain the contacts 4 open position.

I48 and I53 engaged and thus normally retain the stop switch in closedcondition.

An appropriate holding switch is preferably used in conjunction with thecontrol switch just described. That shown in Figs. 21 and 22 hasproven-satisfactory for the purpose. It includes a molded housing I55having mounting ears I56 by which it may be attached to the flanges 61of the bracket plates 68 within the main switch housing II. Within thehousing I55 are two stationary contacts I51 each mounted on a bracketI58 fixed by a screw I59 or I66. The stationary contacts I51 coactrespectively with a pair of movable contacts I6I on the opposite ends ofa metallic bridge piece I62 carried by the squared shank I 63 of aplunger I64 guided for lengthwise movement in a side wall of the housingI55. A pin I65 working in a slot I66 in the housing limits the stroke ofthe plunger I64. A reduced extension I61 of the plunger I64 is guidedwithin the opposite side wall of the housing and a spring I68 thereoncoacts with a collar I69 fixed on the plunger to urge the plungeroutwardly and thus normally retain the switch in A spring I15 on theplunger normally retains the bridge piece I62 against the collar I69,but permits the bridge piece to yield after the contacts I6I have beenforced against the cont-acts I51 by the advance of the plunger I64.

:When the housing I55 of the holding switch is mounted on the bracketplate flanges 61 in the manner above described, the projecting end ofthe plunger I64 lies within the path of travel of the finger I66 carriedby the movable armature 45 of the main switch actuator, so that when thelatter is actuated to close the main switch, the plunger I64 is engagedby the finger I 56 and advanced to force the switch contacts I6I againstthe contacts I51 to thereby close the holding switch, the latterremaining closed so long as the main switch remains closed. The screw I59 which serves to hold in place one of the brackets I58 and its contactI51 also serves as anchorage for an external conductor strip I1I havingtwo binding posts I12 and I13 at opposite ends thereof, so that bothbinding posts are thus'electrically connected to one of the stationarycontacts I 51. The other screw I60 provides anchorage for anotherconductor strip I14 having a binding post I15, so that the latter iselectrically connected to the other stationary contact I51. The housingI55 of the holding switch is also preferably provided with twoadditional binding posts I16 and I1! electrically connected with eachother through a conductor strip I18, but having no electrical connectionwith the switch contacts. The additional .binding posts I16 and, I11serve merely to facilitate the wiring connections. As previously noted,any number of control switches of the type shown in Figs. 18,19 and 20may be employed, one for each control station, and these are preferablyconnected through one holding switch substantially in a manner such aswill now be described. For purposes of illustration, two controlswitches of this type are diagrammatically indicated in the wiringdiagram shown in Fig. 23. As indicated therein, one side of the, controlcircuit I58, containingthe main coil 55, is. connected to the bindingpost I16 on the holding switch housing I55, while the othersideof thecontrol circuit I68 is connected to the binding posts I12.and through itto one arse -v03 of the start switch contacts I39 ef'beth of the controlswitches I28 and also to one of the stationary contacts I51 ofthe-holding switch. The other start switch contact I39 of one of-thecontrol switches is connected through the binding post II5 to the otherstationary contact I5! of the holding switch, while the correspondingcontact I39 of the other control switch is connected through a lead I19to one of the stop switch contacts I48 of the first named controlswitch. The corresponding contact I 48 of the other control switch isconnected through a lead I80 and the binding posts I11 and I76 to thefirstnamed side of the control circuit I08. The other stop switchcontact I68 of each control switch is connected through a lead I8I withthe second named start switch contact I39 of each.

. The arrangement is such that whenever the start switch I39 of eithercontrol switch is closed by pressure applied to either button I30, thecontrol circuit I08 is closed through the stop switches I48 and coil 50,to thereby energize the latter and cause the main switch to close in themanner above described. And as the main switch closes, the finger IDBacts on the plunger I64 of the holding switch I51 to close the same, tothereby maintain the control circuit closed after the actuated startswitch has reopened after releasing the pressure from its'button I '39.

Thereafter, whenever the stop switch 448 of either control switch isopened by pressure applied to its control button I3I, the controlcircuit [08 is thereby opened, to thereby de-energize the coil 50 andopen the main switch. As

the main switch opens the finger I00 moves to 3 and 24, each includes astationary contact H19 and coasting movable contact 182 disposed withina cavity I83 of a molded block I84. In this instance there are two suchswitches, the housing block I84 of each bein attached by a screw I85 orotherwise to one of the bracket pl e 68 e m swit h housing II.

The stationary contact 399' of each switch is carried by a conductorbracket I85 anchored to the block I84 by a screw I81 and having anendprojecting beyond the block and equipped with a binding post I88. The,coacting movable contact I82 is carried by one end of a lever I89 whoseother end terminates in a pair of spaced legs I90 fulcrumed on separatelaterally spaced upstanding ears I9I formed on a conductor bracket I92.The bracket [92 is anchored tq the block I84 by a screw. I93 and isequipped with a binding post I 94 on its projecting end. The

contact I82 is actuated .and controlled by an spaced upstanding ears I98formed on the bracket I92. The spacing of theears I9I. is such as not tointerfere with the swinging action of the lever I90, and the spacing ofthe ears I98- is such as not to interfere with the swinging action ofthe lever I89. Each switch I09 is included in the '12 control circuitI08 through appropriate connections to the binding posts I88 and I94.

The line of tension of the spring I95 is normally disposed on thesameside of the fulcrum points of both levers I89 and I96 and thereforenormally urges both levers to move in the same direction and in suchdirection as to hold the contact I82 against contacti09'. However,whenever the lever I96 is swung so as to shift the line of tension ofthe spring I95 to the other side of the fulcrum point of lever I89, thelatter instantly swings in such direction as to move thecontact'I82-from contact I09 with a Snap action, and'when thexlever I96again moves toward its normal position the contact I82 is again snappedclosed against the contact I709 the instant that the line'of tension inthe spring I95 passes back through .or-to the first named vside of thefulcrumpoint of the lever I89.

Provision is made for rendering each of the switches I09 responsive toan overload condition in one side or another of the work circuit. Thisis accomplished in this instance by rendering the leverl 9B responsiveto a bi-metallie thermal strip I99 which in turn responds to thetemperature of an adjacent resistance coil 200 which is connected in-oneside '20I of the work circuit. The thermal strip I99 and coil 200areshown arranged side by side in a cavity 202 formed in the block I84and closed by a cover plate 203 of insulating material removablyattached to the block by end screws 204 ,orthe like. The coil 200 isfixed in place by the screws 204 and electricalls/connected within oneside of the work circuitthmughsuitabIe terminals 205 at opposite endsthereof. The thermal strip I 99 is supported at one end by a suitablebracket 20S, adjustably mounted within the block I84 by screws 201 and208, and bears at its other end against athrust pin 299lengthwisemovable within the block and bearing against the end of the lever I96.

The arrangement is such that in the event of an overload in the workcircuit the thermal strip I99 will flex in response to the heatdeveloped in the coil 280 and force the'pin 209 and lever I in suchdirection as to cause the switch contact I82 to withdraw from contactI09 with a snap action in the manner above described, to thereby breakthe control circuit I08 and cause the main switch to open, The degree oftemperature and consequently the degree of overload at which this actionwill occur maybe regulated by adjustment of the bracket 206, and thismay be accomplished by adjusting one or both of the screws 291 or 209.

Each'overload switch I09 is preferably so constructed and arranged thatit will not automatically reclose after it has opened in response toanoverload condition, so as to prevent rcclosin of the main switch untilopportunity has been had to discover and correct the cause of theoverload. For that purpose the contact carrier lever I89 is normallypermitted an opening movement so extensive that when that lever is'infull switchopen position the movement of the lever I96 is insufficientto: shift the line of action of spring I through and past the fulcrumpoint of the lever !89 and thus unable to effect a closing action of thelever I89. To effect such a closing action, amanual reset mechanism isprovided for each switch. Mechanism well adapted for that purpose isshown in Figs. '3 and 4.

Each reset mechanism shown comprises a thrust pin 2I0 which projectsinto the cavity I83 behind the free end of the contact carrier leverI89. The pin 2I0 normally assumes a retracted position toward which itis urged by a spring H I. The pin 2I0 bears outwardly against a rockerplate 2I2 fulcrumed on a screw 2I3 fixed in the bottom of the switchblock I84. A plunger 2I4 is operable to tilt the rocker plate 2I2 insuch direction as to thrust the pin 2N3 further into the cavity I83toward the position shown in Fig. 3 so as to advance the switch leverI89 from a full open position into or toward the closed switch positionshown in said figure. Each plunger shown at 2I4 comprises a flat stripof Bakelite confined between the switch block I34 and its supportingbracket plate 68 and guided within a channel formed in the rear face ofthe block I84.

If desired, the reset plungers 2I4 may be adjustably positioned so as tohold the pin 2I0 in an advanced position, to thereby limit the outwardswing of the contact carrier lever I39 to a point from which it mayautomatically swing inwardly to close the overload switch whenever thelever I98 is returned to switch-closing position. For that purpose eachplunger 2I4 is slotted to receive a clamp screw 2I5 carried by astationary clamp 2I6. By virtue of this arrangement, either or both ofthe reset plungers 2 I 4 may be releasably retained by its clamp screw2I5 in an inwardly advanced position, so as to limit the outward swingof the lever I89 by the advanced position of the thrust pin 2I0maintained by the advanced plunger.

In order that the thermal unit I99 of each overload switch I09 may beisolated from external conditions and thereby substantially uninfluencedby temperatures other than those developed by the adjacent resistanceelement 200, the side of each supporting block I84 is preferably coveredby an appropriate side panel 2I I, attached thereto by screws 2I8 or thelike, and removable to provide ready access to the housed parts.

Provision is preferably made for the simultaneous operation of bothreset plungers 2I4 by means operable outside of the main housing II. Inthis instance the means for that purpose comprises two resilient metalstrips 2 I 9 (Fig. 2) each overlying the end of one of the plungers 2I4and each attached at one end 220 to the inner face of the housing cover.The opposite free ends of these strips are connected by a cross-bar 22I. A push-button 222, fixed to the cross-bar 22I substantially midwaybetween the strips 2I9, normally projects through an appropriate opening223 in the housing cover.

The arrangement is such that by depressing the push-button 222 bothstrips 2 I9 may be forced inwardly in a manner to simultaneously depressboth plungers 2I4 and thereby insure closing of both overload switchesI09 in the above-described manner.

Various changes may be made in the invention herein above specificallydescribed Without departing from or sacrificing the advantages of theinvention as defined in the appended claims.

I claim:

1. In an electromagnetic controller the combination of a main switch,electromagnetic means for actuating the same, a control circuit for saidmeans, said circuit including a control switch operable to close saidcircuit and thereby energize said means, means biasing said controlswitch toward open circuit position, and other electromagnetic meansresponsive to energization of said first named means and operable uponsaid control switch to maintain said circuit closed.

2. In an electromagnetic controller the combination of a main switch,electromagnetic means for actuating the same, a control circuit for saidmeans, said circuit including a single switch operable to make and breaksaid circuit and biased toward circuit breaking position, and otherelectromagnetic means responsive to energization of said first namedmeans for holding said last named switch in circuit making position.

3. In an electromagnetic controller the combination of a main switch,electromagnetic means for actuating the same, a control circuit for saidmeans including a single switch operable to make and break said circuitand biased toward open position, and other electromagnetic meansresponsive to energization of said first named means for holding saidlast named switch closed, said last named means including connectionsyieldable to permit manual opening of said last named switch against theholding action of said last named electromagnetic means.

LYLE BEEMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,051,219 Grabau Jan. 21, 19131,491,396 Hall Apr. 22, 1924 1,513,247 James Oct. 28, 1924 1,530,929Brobst Mar. 24, 1925 1,714,085 Getchell May. 21, 1929 1,726,233 KrantzAug. 27, 1929 1,763,284 White June 10, 1930 1,893,827 Getchell Jan. 10,1933 1,912,610 Widmer June 6, 1933 1,981,534 Wilms et a1, Nov. 20, 19341,986,445 Parsons et al Jan. 1, 1935 1,997,550 OLeary Apr. 9, 19351,998,810 Getchell Apr. 23, 1935 2,013,013 Van Valkenburg Sept. 3, 19352,087,895 Bierenfeld July 27, 1937 2,134,593 Wulsten Oct. 25, 19382,254,768 Bierenfeld Sept. 2, 1941 2,261,632 Rosing et al Nov. 4, 19412,307,776 Grant et a1 Jan. 12, 1943 2,318,095 Putman May 4, 19432,335,888 Stilwell Dec. 7, 1943 2,371,601 Beeman Mar. 20, 1945

